Aug 24, 2018

Python has two handy functions for creating lists, or a range of integers that assist in making for loops.These functions are xrange and range. But you probably already guessed that! 🙂

The Difference Between xrange and range in Python

Before we get started, let's talk about what makes xrange and range different.

For the most part, xrange and range are the exact same in terms of functionality. They both provide a way to generate a list of integers for you to use, however you please. The only difference is that range returns a Python list object and xrange returns an xrange object.

What does that mean? Good question! It means that xrange doesn't actually generate a static list at run-time like range does. It creates the values as you need them with a special technique called yielding. This technique is used with a type of object known as generators. If you want to read more in depth about generators and the yield keyword, be sure to checkout the article Python generators and the yield keyword.

Okay, now what does that mean? Another good question. That means that if you have a really gigantic range you'd like to generate a list for, say one billion, xrange is the function to use. This is especially true if you have a really memory sensitive system such as a cell phone that you are working with, as range will use as much memory as it can to create your array of integers, which can result in a MemoryError and crash your program. It's a memory hungry beast.

That being said, if you'd like to iterate over the list multiple times, it's probably better to use range. This is because xrange has to generate an integer object every time you access an index, whereas range is a static list and the integers are already "there" to use.